Research On The Effect Of Rare-earth Salts On Performance Of Zinc-flake Coating

Zinc-aluminum Flake is a new anti-corrosion technical which can instead of Galvanized and Zinc alloy,paint on substrate by physical process with no electronic,to get a close and homogeneous coating.In this paper,zinc-flake coating was prepared by coating method,zinc flake,aluminum flake,2-ethyl-1-hexanol titanium(4+)salt,vinyl trimethoxy silane,2-butanol-ethanol,1-methoxy-2-propanol as the main components of zinc aluminum coating,The effects of cerium ammonium nitrate,cerium oxide,cerium chloride,lanthanum nitrate and dysprosium oxide on the film thickness,coating amount,adhesion and corrosion resistance of zinc-aluminum coating were studied.The influence of the addition of rare earth salts on the performance of Zn-Al coating was analyzed by measuring film thickness,coating amount,adhesion,neutral salt spray,and Sem&EDX characterization.The research results are as follows:1)Appropriate addition of cerium ammonium nitrate can effectively improve the corrosion resistance of the coating.When the addition amount of cerium ammonium nitrate reaches 20 g/L,the corrosion resistance of the coating reaches the highest value,which reaches 1176 h.About 50% longer than normal coating.Ammonium cerium nitrate is slightly dissolved in solvents,and in most cases exists in the form of fine particles in the coating.The corrosion resistance of the coating is improved by the passivation of metal powder.2)Cerium oxide exists in the form of particles in the coating,which mainly plays a shielding role.When a small amount is added,the corrosion resistance of the coating can be improved to a certain extent.3)The addition of cerium chloride will significantly reduce the corrosion resistance of the coating.The main reason is that the rare earth salt contains Cl-,which has the characteristics of small atomic radius and strong penetration ability,so it is easy to penetrate the coating to the substrate,resulting in pitting corrosion.4)Lanthanum nitrate mainly exists in the form of particles in the coating.It through its own strong oxidation,as a passivating agent passivating around the metal powder,so that the surface of the dense oxide layer,a time to improve the corrosion resistance of the coating.Adding less than 12 g/L has no obvious effect on coating thickness and coating amount.